They're from around Chattanooga. Lookout Mountain, actually. There's three sisters, used to play at the Mountain Opry on Signal Mountain on Friday nights (one of the venues I documented back when I had the little studio). I think they all headed off to college and one decided to go a different direction (not even musical) so the remaining two sisters are Larkin Poe. It's a combination of family names, if I understand correctly.
And yes, they kick ass. They've played the new version of Riverbend now and the new festival in town, Moon River, which became the model for the rejuvenated Riverbend festival.